Sinclair's
newest brainchild could restructure the entire
industry. We bring you the latest details

SINCLAIR'S
ZX84

Sinclair's latest computer
does for the professional market just what the ZX80, ZX81
and Spectrum have done for the home micro market.

When those early machines
were released, they caused a furore in the computer
industry by offering capabilities comparable with those
of existing machines, but at vastly lower prices. This
was usually achieved by packaging the components in a
rather ingenious way - often replacing the conventional
circuitry used in most micros with custom-designed ULAs.
An uncommitted logic array is very expensive to design
and put into production, but over a long production run
using a ULA to take over the functions of conventional
components makes the computer much cheaper as well as
smaller and lighter.

Sinclair's newest machine,
the ZX83/ZX84 (the name depends on who you talk to within
Sinclair Research) does all this and more. Until now, the
packaging com-promises have made ZX computers rather
unpleasant to use in some respects - the keyboards in
particular have always come in for severe criticism from
the computer press and end-users alike - and these
limitations have always held the computers back from the
more serious applications which their internal components
could handle.

The ZX84 may well be cheap
- under £400 for the basic version - but its external
attributes are far from nasty. And if you think that
£400 is a lot of money to pay for a computer, then
that's only because it is natural to assume that the ZX84
replaces the Spectrum in the same way that the Spectrum
replaced the ZX80 and the ZX81 supplanted the ZX80. This
is not the case.

For the first time,
Sinclair is moving into what has hitherto been regarded
as the 'small business' market. The computer is far more
powerful than anything remotely near its price range,
leaving even relative newcomers like the IBM PC Jr (see
page 34) in the shade.The processor at the heart of this
powerhouse is a heavily customised chip similar to the
Motorola MC68000, the market leader in 16/32 bit
processors (one jump ahead from the IBM Personal/Sirius
level of technology).

One of the advantages of
using a processor of the calibre of the 68000 is the
enormous amount of memory which can be addressed
directly. Eight-bit micros like the Newbrain and Elan
which claim to be able to address megabytes of RAM do so
only by paging it in and out, 64K at a time, with bank
switching. On the most basic ZX84 you get 128K, twice as
much as on the most capacious rivals, and this amount
will be easily expandable.

Anyone dealing with a
micro which has a minimum memory of 128K is likely to
find him - or herself playing around with much larger
files than would be necessary or even possible on a
Spectrum. This is when the cassette interface which has
served micro users for so long finally ceases to be a
viable proposition.The ZX Microdrives are much nearer the
mark, with their high-speed operation making life
relatively bearable, but their capacity of only 85K per
cartridge is still rather marginal. Either the
Microdrives are going to have to get bigger, or some
other type of simple mass storage will have to be found.
One other alternative, as our illustration opposite
shows, is to use four microdrives to increase capacity.
Detachable battery-powered RAM packs are one interesting
possibility these are already used on some portable
computers) and the CMOS architecture makes for the low
power consumption needed.

At the moment, the lack of
a built-in display prevents the ZX84 from being truly
portable, but it would be an easy step to take with a
later version. The prices of liquid crystal displays are
falling sharply, and this type of display would be much
more likely than the Sinclair flat screen, which does not
really lend itself to computer applications.

A big plus for some
potential users (and a feature which is bound to become
more widespread in the near future) is the option of an
on-board modem similar to the internals of the Prism VTX
5000 unit which many Spectrum owners already use to log
on to Prestel through Micronet 800.

Our unofficial sources
indicate that the Z80 processor which has been used in
all ZX computers so far will not disappear from the new
model. With two-processor computers now increasingly
common, retaining the Z80 makes it easy to transport the
Microdrive operating system to the new machine.

The upward price limit for
such a flexible system will be decided largely by the
number of optional extras the user feels he needs, but
with Sinclair Research girding its loins for an offensive
on Acorn's position as manufacturer of the sole BBC
approved computer, it is safe to assume that prices for
roughly comparable BBC Micro and ZX84 systems (ignoring
the Sinclair micro's superior processing capabilities)
will tie up closely..